The present invention is particularly concerned with coiled fastener packages of the type disclosed in U.S. Pat. No. 3,083,369. The coiled fastener package shown therein is formed by wrapping in a coil formation an assembly which includes a multiplicity of fasteners, each having a shank with headed and pointed ends and an elongated carrier supporting the fasteners in parallel relation with respect to one another in transverse relation to the longitudinal extent of the carrier. The carrier disclosed in the patent consists essentially of two parallel weldable wires which are extended across the fastener shanks and welded thereto. The present invention also relates to coiled fastener packages utilizing other carriers as, for example, the plastic strip carrier disclosed in U.S. Pat. No. 3,438,487 and the coiled package formed therefrom as disclosed in U.S. Pat. No. 3,450,255.
An advantage of the parallel wire carrier over the plastic strip carrier is that a significantly greater fastener density can be embodied in a given size coiled package. This greater fastener density is achieved by virtue of an increase in the number of volutes or turns into which the assembly can be wrapped in any given size coil formation. Stated differently, with a parallel wire carrier, the fasteners of adjacent volutes can be brought into abutting engagement to the extent that heads overlap. On the other hand with the plastic strip carrier, the plastic strip serves as a spacer between the fasteners of adjacent volutes to the extent of providing head spacing.
An advantage of the plastic strip carrier over the parallel wire carrier is that the assembly can be wrapped in a flat coil formation wherein the fastener heads are disposed generally in a single plane because they are spaced from one volute to the next. On the other hand, the parallel wire-fastener assembly required overlapping the fastener heads from one volute to the next because of their abutting relationship. The result was that the coiled package had one end which was concavely frustoconical while the other was convexly frustonconical. Coiled fastener packages with this end configuration are referred to as "domed". Usually, the head end was the domed end.
These domed packages presented particular difficulties in shipping. Heretofore, in order to prevent damage in shipping, it has been necessary to provide a molded foam plastic (EPS) tray in supporting relation to a series of domed packages along their bottom ends and a different complementary molded foam plastic tray in engagement with the top domed ends. The top molded tray included concave surfaces for receiving the convex domed headed ends of the fastener packages, while the bottom molded tray included convex surfaces for entering the concave pointed ends of the fastener packages. In this way each coiled package was firmly supported. The molded trays added significant costs, presented storage difficulties because of the fire hazard presented (toxic fumes) and presented disposal problems because of being incapable of safe burning and a disposable problem because the trays are not biodegradable.
With the recent development of a method of wrapping the parallel wire-fastener assembly into a relatively flat ended coil package without sacrificing density, it became necessary to modify the plastic trays to accommodate the flatter ends. The improved method of wrapping and improved flat ended package obtained thereby is disclosed in U.S. patent application Ser. No. 558,533, filed Dec. 6, 1983, the disclosure of which is hereby incorporated by reference into the present specification. Briefly, it will be noted that the flatten end fastener package is obtained by changing the lapped relationship of the heads in each volute with respect to the heads in the preceding volute, that is, first overlapping, then underlapping, then overlapping, etc.